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;. ss..s,"M'.fc:..,.a...oaPa..-...., w,�w_—4"VA_A -• _ _" _. ..`+:::�..':'y .:.`mow ,C:.:s - .xr. ::_�"" --.: e -s:: _,. __` _ nK„- �;. fi=r - r ;i 4y µ. ;s. l}�rurtsit�. Tier TA11t.r riemn not Include ouch information an the dotectitsn h'Atm at which other compouhdn were not detected. film full toot til tiro ,at,orntory relx.)rt will ho found In Section Foch of thin report. G6:NF:RAL ADVISORY O.'i POSIT1VH FIRS )1.Ts Though our firm iapocializr-te ire Man, pling, monitoring and documentation, rather thnn Intorpretation and ramadintion, we have been asked by the anglncoring reiaff of the Pegtonal Water quality Control Board to include In our reprrtis an advisory nectlon outlining the genoral types of ndditional actions which may be) required when contamination In found. 'Thio advisory In not intended to characterize conditions at thin particular nits or replace the, sorvicen of n consulting firm specializing in the Investigation, characterization and err etlintion Of ouch ronditionn no may eziat. Rather, it in intended to ndviasa, YOU that ouch ndditionail actions way firs required even though come time mn> shpt- beforo you are contacted by one of the ante$rented regulatory 3 In limon 2 (which (o regulated by they Scan Francisco Regional Wntar quality Central 1Jo-4rd,) the thresholds earn readily defined in the Board's 13uhlication, f9r Addretieinrt Biel l,enlfl ,according IA this document, stall which hots less than 100 parts per million total petroleum fuel hydrocarbon ITPII) contamination docs not generally require immediate additionai action. hoard enginesers emphasize that this do's s not mean that Borne+ action mlght not be required in the future. Still, the site is assigned ax low priority unless it is situated in an area of high hydrogeologic concern. The detection of more than 100 ppai TAH in the native Boll beneath a tank In generally considered grounds for requiring an additional investigation in the form of roil barings Find installation of at least one groundwater monitoring well followed by perlodic monitoring. The detection of ICIO t ppm Tpll is usually viewed by the Board an an unacceptable level of fuel saturation which will mandate excavation of the affected ground dorm to the turtheat practicable reach of conventional excavating machinery followed by soil borings and Installation of groundwater monitoring wells. Other regions use different standards for determining when a groundwater Investigation will be required. For example benzene is often used in lieu or TPIL Evtn very lora levels of benzene are often seen as grounds for requiring a subsurface investigution. This criteria may be relaxed or stiffened depending on the location of the site in relation to different groundwater aYateano, the depth to water, type of soil, and the concentrations of benzene Involved. The above standards ripply an.ly--to-fuele<..-.-t:hen-inmplesAaken_in-con tictn---- - ------- --- - -- --- --- ---- -- with a-waste all tank or a solvent tank are found to contain even snu,il amounts of any of the SAA priority pollutants touch as TCE, PCI:, ACE etc. which are detected by EPA methods 8010, 8020, and 8240) more stringent standards are often applied. In thaase catses, soil borings and monlLiring well Installation may be required If there is any detectable amount of any of Ssmpltng Report 1380;7-C-1 Chevron 1918 SIMTION TWO/page 12